Hammering the point that Texas is looking more Hispanic and less white every year, Democrats on Monday began pushing for new 2018 election maps before a court that already decided Republicans purposefully tried stifling minority voters.

The outcome of the trial in San Antonio could have stakes that reverberate nationally, similar to other redistricting battles playing out elsewhere in the U.S. Democrats trying to reclaim Congress next year in the first midterm elections under President Donald Trump could boost their odds of picking off a handful of Republican seats in Texas if new maps are ordered.

The trial also puts Texas on the defense over voting rights again. Two federal courts in April concluded that Republican lawmakers sought to dampen the growing influence of Hispanics and blacks at the ballot box by adopting a voter ID law and drawing maps that overwhelmingly favored GOP candidates.

Booming Texas has four of the five fastest-growing cities in the nation, including Dallas and Houston, a surge being driven by Hispanic growth. Minority rights groups began the trial with analyses they say shows Hispanics and blacks voting as a coalition in recent elections to back Democrats.

A former Democratic state lawmaker, Trey Martinez Fischer, testified that Republicans rushed during the summer of 2013 to permanently adopt voting maps that a court had tweaked for the election a year earlier. Opponents decry those maps as a quick fix that didn't purge all districts of the use of gerrymandering - the practice of drawing boundaries to favor one political party over another - in a racially biased way.

State attorneys challenged the methodology of the studies showing racial polarization and suggested data was cherry-picked. Texas is not expected to begin calling its witnesses until later this week.

Republican Texas Attorney General Ken Paxton's office argues in court documents that there is no evidence showing that the maps implemented by the court and later adopted by lawmakers were discriminatory.

It is not clear when the three-judge panel will decide whether Texas' maps need tweaks before 2018. Other states could also have districts redrawn before next year, including North Carolina, where Republican leaders said last week that they're prepared to carve new lines for 2018 after the U.S. Supreme Court found racial gerrymandering.

Jose Garza, an attorney for the Mexican American Legislative Caucus, has said he believes at a minimum that two or three congressional districts in Texas and between two and five Statehouse districts in Texas should be redrawn to better favor minority voters.

The groups suing Texas also want the state to become the first to be put back under federal oversight since the U.S. Supreme Court struck down key parts of the Voting Rights Act four years ago. That 2013 ruling struck down a provision in the 1965 law that required Texas and other states with troubled histories of racial discrimination to “preclear” any voting law changes with the federal government before enacting them.

An Associated Press analysis in June found that districts drawn by Texas' Republican-controlled Legislature helped the party win nearly four more U.S. House seats than it otherwise would have in the last election, which was more than any other state. The AP scrutinized all 435 U.S. House races in November using an “efficiency gap” statistical method designed to calculate partisan advantage.